Imaging the Plio-Quaternary submarine geomorphological evolution of the Gulf of Cagliari

Abstract

Based on the morpho–bathymetric data coming from the MaGIC project (Marine Geohazards along the Italian Coast) and the high-resolution seismic reflection profiles acquired in 2010 by OGS-Explora, we depict the complex geomorphology of the Gulf of Cagliari and the evolution of the most striking morphosedimentary features developed during the PQ. The seafloor is shaped by the canyon system, the Sarroch and S. Elia-Foxy canyons. The obtained results point that their onset and location do not coincide with paleoincisions formed by the Messinian erosion. The main pathway changes of the Sarroch canyon are conditioned by extensional tectonics of the Campidano Graben and are controlled by the Banghittu High. Cut-and-fill features and infill deposits indicate that retrogressive erosive processes affect the canyon heads and produce landslides. transport deposits in the basin. In fact, four large MTD's have been recognized and analysed within the PQ sequence. They show different seismic facies, from transparent to chaotic, and are locally affected by internal deformational structures which allow us to distinguish the translational and compressional domains. The interplay between the morphosedimentary evolution of the systems canyons and the MTDs are useful to understanding the role played by the downslope channelized and non-channelized sedimentary processes over time and to explore the factors, local and/or global, controlling their occurrence and/or predominance. This analysis of the submarine canyon morphologies and occurrence of MTDs can help evaluate the potential geo-hazard implications of the region.